In the mining industry there is a continual effort to lower the cost of extraction of ore or overburden. A competition in the cost calculation exists between operating earth or ore extraction equipment at a maximum capacity and the damage caused to the equipment by overloading or fatigue. Manufacturers of mining equipment typically seek to protect themselves from liability for equipment failure by specifying conservative operating conditions that attempt to keep the failure rate very low, whereas the interest of the mine operator is to find the most economical balance between ore extraction and damage that minimises the cost per tonne of ore extraction.
Manufacturers and third party providers provide a range of monitoring systems to provide information on loads and relative stresses experienced by draglines, utilising strain gauges on certain representative structural components. Using such systems it is possible to record a time profile of the strain measured at the strain gauges and thereby provide reports on how the strain varies from one time period relative to another, enabling relative comparisons to be made between different operators and operating conditions and information on which time period produced relatively more stress/damage at the measured locations compared to another. While useful, such relative information cannot advise on how close the equipment is to failure or how much damage is occurring through fatigue. Without such information, the monitoring system is of limited use in assisting the mine operation and equipment operator in their goal in cost-efficiently maximizing production while minimizing damage to the equipment.
According to the current state of public knowledge in the art, monitoring systems that can usefully advise in real-time on whether the structure is operating within the design limits, the actual closeness to failure or the actual rate of cumulative damage, is not available. The current systems provide a relative measure which could lead to inaccuracies that could result in frequent false alarms and warnings.
There is therefore a need to provide an improved monitoring system that can provide such information.
Through an accumulation of long standing experience and research, the inventor has realized that enabled by careful observation and structural analysis as described herein guiding the placement, calibration and interpretation of strain gauges, a monitoring system can be provided that can surprisingly provide such reliable direct advice, in real-time to an operator and to mine management.